Swashplate pump incorporating a dual location cluster bearing

ABSTRACT

A swashplate style pump uses a dual location cluster bearing of consistent configuration for use in each of two positions in the pump. In one location the dual location cluster bearing will interface with pistons and the swashplate cam. In a second location the dual position cluster bearing will interface with the non-camming side of the swashplate and the back plate of the pump. The dual position cluster bearing can be used in either and both positions with equal facility.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention has to do with swashplate pumps and specifically with adual location and dual purpose cluster bearing that in one position inthe pump acts as a bearing between the relative bottom surface of thepump swashplate and in a second position in the pump as a cam followerinterfaced between the pistons of the pump and the inclined swashplatedrive cam. The dual location cluster bearing is formed as a single pieceof non-metallic material replacing multiple cam thrust bearings and amulti-part cam follower in the prior art.

2. Description of the Prior Art

Swashplate pumps have been in use in the fluid pumping field for manyyears. They are typically used in pumping fluids wherein a non-pulsedoutput stream is desired. This style of pump is efficient and does nothave the pumping losses sometimes inherent in pumps of other designs.The closest prior art to the invention presented herein is the "Delpump"formerly manufactured by CHPT Incorporated as disclosed further on inthis specification.

A cluster bearing of the type used in this invention is disclosed inpending U.S. application Ser. No. 08/611,315.

SUMMARY OF THE INVENTION

As stated above, the invention resides in an improvement to swashplatepumps and specifically those swashplate pumps with multiple componentsused in making up the bearing surfaces between the pistons of the pumpand the inclined swashplate drive cam in one location and the relativebottom of the swashplate and the pump housing on the other hand. Thedual location cluster bearing used in the invention presented herein isformed from a single piece of non-metallic material replacing multiplemulti-part cam followers and cam thrust bearings in the prior art. In afirst location in the swashplate pump the dual location cluster bearingincludes a surface that will receive the arcuate ends of the pistons ofthe pump and the obverse surface will include bearing surfaces thattransmit the load from the inclined cam surface of the swashplate to thepump pistons. The second location for use of the dual location clusterbearing is at the bearing surface between the swashplate and the housingof the pump. This is primarily a generally flat surface and the portionsof the cluster bearing that would normally receive the ends of thepistons will be located in a groove, channel or recess formed in theinboard surface of the housing or back plate below the swashplate thrustzone. The second cluster bearing is generally upside down relative tothe first cluster bearing.

An advantage of the dual location cluster bearing is that it will beused in either of two places in the host swashplate pump. It is onepiece part that has two separate uses in the pump. By its unique shapeit can be used with equal facility in either of the two locationsthereby eliminating the need for separate bearing assemblies for eachlocation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is graphically presented by several drawing figuresincluding the following figures:

FIG. 1 is a cross sectional view of a swashplate pump incorporating theinvention;

FIG. 2 is a top view of the dual location cluster bearing;

FIG. 3 is a view of the dual location cluster bearing taken through 3--3of FIG. 2;

FIG. 4 is the obverse side of the dual location cluster bearing shown inFIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Swashplate pumps of the type incorporating the invention set forthherein are well known in the industry. The specific pump to which thisimprovement applies is FMC Corporation's "Series C Composite PistonPumps" previously manufactured under the trademark Delpump by CHPTIncorporated. U.S. Pat. No. 5,013,219 applies to this pump. The pump isdescribed in literature available from FMC in Houston, Tex.

Looking at FIG. 1, a sectional view of a swashplate pump, generally 10,is shown. A body 12 is capped with a check valve housing 14 which inturn is capped with a gallery 16. A cam spacer 18 supports the body 12away from back plate 20 providing a cavity for the cam subassembly orswashplate 22. Hex nuts such as 24 will clamp the gallery 16, checkvalve assembly 14, body 12, cam spacers 18 and the back plate togetheras shown in FIG. 1.

A piston 26, one of several, generally between five and twelve in numberdepending on pump capacity, which in used in a pump of this type iscarried in a lined cylinder 28 in the body 12. This piston 26 will beurged to travel reciprocally in the lined cylinder 28 by the well knownprincipal of the camming action of the swashplate design pump. Fluid tobe pumped will enter the pump 10 through inlet fitting 30 and be pumpedout of the outlet fitting 32. Check valves such as 34 and 36, one set ofcheck valves associated with one each of said pistons 26, will controlflow of the pumped fluid into and out of the pump.

The cam 22 includes an extended portion 38 which is the mechanical driveinput shaft for rotating the integral cam 22 and shaft assembly.

The first location for the two dual position cluster bearings 46 in theswashplate pump is between the piston 26, actually the arcuate endportion of the piston, and the flat cam surface 48 of the cam 22. Thecluster bearings, one shown as 40 and the second one shown as 46, asshown in the sectional view of FIG. 1 are shown removed from the pump inFIGS. 2, 3, and 4. The dual position cluster bearing from the pistoncontacting location has been selected as the one that the drawingfigures are based on.

The second place that the dual position cluster bearing, a clusterbearing shown as 40, is used in this swashplate pump is between the backplate 20 and the relative bottom side of the swashplate 22. In FIG. 1the back plate 20 is shown with a cavity such as 42. This cavity can bea circumferential groove or channel machined or otherwise formed in theinboard surface of the back plate 20. The channel 42 is circumferentialaround the center of the pump relative to the major axis of theswashplate drive shaft.

In these figures the cluster bearing is shown with the piston receivingbearing cups, such as 50, which are concave receivers which accommodatethe arcuate ends of the pistons 26. Five piston receiving bearing cups50 are shown in the cluster bearing 46 of FIG. 2; however, this numberis dependent on pistons and the pump and would normally be between fiveand twelve in today's production pumps. The bearing cups 50 are formedintegrally into a web of material and the piston cups, indentations inthe web, are axially spaced around the web.

The obverse side (from FIG. 2) of the cluster bearing 46 is shown inFIG. 4. In this figure items such as 52, there are five shown, arethrust bearing surfaces which are generally "under" and aligned with thepiston receiving bearing cups 50. They will provide thrust bearingsurfaces that ride proximate to the flat cam surface 48 of the cam 22.When the dual position cluster bearing is in the position between theback plate and the relative bottom of the swashplate these thrustbearing surfaces will contact the swashplate. When in the pistoncontacting position these thrust bearing pads or surfaces 52 will absorbthe discharge and suction pressure load on the pistons. They will rideon the inclined surface of the rotating cam and will be lubricated witha naturally forming hydrodynamic film of water or other liquid toseparate the surface of the cluster bearing from the surface of therotating cam. The preferred material for the single piece injectionmolded dual location cluster ring is Arlon 1555 PEEK. If the lubricationbetween contact surfaces of the dual location cluster bearing and camexperience a drop in viscosity or transient load conditions that createcontact between the dual location cluster bearing 46 and the cam surface48, the carbon filled PEEK cluster bearing will provide lubrication.

On the obverse side of the cluster bearing the areas between the thrustbearing surface pads 52, the relief zones such as 54, are relativelylower than the thrust bearing surfaces 52. A slight ramp, such as 56 isformed to transition between the relief zones 54 and the thrust bearingsurface pads 52 on both sides of the pads.

The inventors contemplate that the method of assembling a swashplatetype pump in which this dual location cluster bearing will be used willbe, in pertinent part, as follows. The swashplate style pump willinclude a pump having a back plate with a bearing receiving channelformed into it and a swashplate having a camming surface and anon-camming surface. As is common practice, multiple pistons will becarried adjacent the camming surface of said swashplate. The steps ofthe method of assembling the pump will include selecting a first clusterbearing from a set of cluster bearings for installation in saidswashplate pump, installing the selected first cluster bearing in aposition in the pump between the camming surface of the swashplate andthe pistons, selecting a second cluster bearing from a set of clusterbearings for installation in the swashplate pump, and then installingthe selected second cluster bearing in a position in the pump betweenthe non-camming surface of the swashplate and the back plate of thepump. The set of dual location cluster bearings will include, in apreferred embodiment, a collection of interchangeable dual locationcluster bearings.

In summary the invention presented herein is for use in a swashplatetype pump. The pump includes a back plate and a swashplate with theswashplate having a camming surface and a non-camming surface andmultiple pistons carried adjacent the camming surface of the swashplate.The improvement over the art includes a first cluster bearing locatedbetween the camming surface of the swashplate and the pistons. Thisfirst cluster bearing has a plurality of piston receiving bearing cupsand a plurality of thrust bearing surfaces on the side of the clusterbearing obverse from the side in which the piston receiving bearing cupsare formed. A second cluster bearing is located between the non-cammingsurface of the swashplate and the back plate of the pump. This secondcluster bearing has a plurality of piston receiving bearing cups and aplurality of thrust bearing surfaces on the side of the cluster bearingobverse from the side in which the piston receiving bearing cups areformed just like the first cluster bearing. The point of the inventionis that each of these two bearings come from the same set of bearingsand can be used in either position with equal facility.

It is believed that the foregoing explanation and description, when readin juxtaposition with a review of the drawing figures, of the inventionprovides a full teaching of the invention. The inventors recognize thatdesign changing the cluster bearing are possible, such as the use ofdifferent material having similar properties to the preferred materialherein. It is expected that the following claims will cover such nuancesof design and product selection.

What is claimed is:
 1. A swashplate type pump, said pump including aback plate with a bearing receiving channel and a swashplate, saidswashplate having a camming surface and a non-camming surface, multiplepistons carried adjacent said camming surface of said swashplate, theimprovement comprising:a first cluster bearing located between saidcamming surface of said swashplate and said pistons, said first clusterbearing having a plurality of piston receiving bearing cups and aplurality of thrust bearing surfaces on the side of the cluster bearingobverse from the side in which the piston receiving bearing cups areformed; a second cluster bearing located between said non-cammingsurface of said swashplate and said back plate of said pump, said secondcluster bearing having a plurality of piston receiving bearing cups anda plurality of thrust bearing surfaces on the side of the clusterbearing obverse from the side in which the piston receiving bearing cupsare formed.
 2. The invention in accordance with claim 1 wherein saidsecond cluster bearing is positioned in said bearing receiving channelwith said thrust bearing surfaces contacting said non-camming surface ofsaid swashplate.
 3. The invention in accordance with claim 1 whereinsaid second cluster bearing is positioned in said bearing receivingchannel with said piston receiving bearing cups contacting saidnon-camming surface of said swashplate.
 4. The invention in accordancewith claim 2 wherein each of said first and said second cluster bearingsare interchangeable.
 5. The invention in accordance with claim 4 whereinsaid first cluster bearing thrust bearing surfaces will contact saidcamming surface of said swashplate and said second cluster bearingthrust bearing surfaces will contact said non-camming surface of saidswashplate.
 6. A method of assembling a swashplate type pump, said pumpincluding a back plate and a swashplate, said swashplate having acamming surface and a non-camming surface, multiple pistons carriedadjacent said camming surface of said swashplate, comprising the stepsof:selecting a first cluster bearing from a set of cluster bearings forinstallation in said swashplate pump; installing said selected firstcluster bearing in a position in said pump between said camming surfaceof said swashplate and said pistons; selecting a second cluster bearingfrom a set of cluster bearings for installation in said swashplate pump;installing said selected second cluster bearing in a position in saidpump between said non-camming surface of said swashplate and said backplate of said pump; wherein said set of cluster bearings from which saidfirst cluster bearing is selected is the same set of cluster bearingsfrom which said second cluster bearing is selected; wherein said clusterbearings of said set of cluster bearings have a plurality of pistonreceiving bearing cups and a plurality of thrust bearing surfaces on theside of the cluster bearing obverse from the side in which the pistonreceiving bearing cups are formed.